1. Field of the Invention
The invention relates to a submersible hollow shaft motor and to a submersible floating aerator comprising a submersible hollow shaft motor.
2. Description of the Related Art
Liquid aeration is used in the treatment of liquids for the purpose of mixing in air and increasing the dissolved oxygen (DO) content of the liquids. When liquid aeration is used as part of a wastewater treatment, bacteria and other microorganisms are usually added to the liquid as well to breakdown organic matter within the wastewater. In other applications, aeration processes are used in the treatment of water to meet the dissolved oxygen requirements for supporting fish and other aquatic organisms, for example, in aquaculture.
Conventionally, apparatuses used for liquid aeration include surface aerators, diffuser/blowers, and rotor aerators. Surface aerators pump water upward and throw it into the air. They require high horsepower and consume high amounts of energy to pump liquids against the force of gravity. In blower/diffuser systems, compressed air is introduced through diffusers at the bottom of a basin. Relatively high power is required to pressurize atmospheric air to overcome the liquid head resistance. Oxygen rises vertically and escapes quickly before effectively dispersing into the liquid. Rotor aerators consist of rotating aerators positioned at the surface of the liquid receiving treatment. Rotor systems have been known to be expensive to maintain and are high in energy consumption. They throw liquid into the air, creating aerosol that releases malodors. Rotor systems are often used in oxidation ditch applications.
The problems with conventional aerators include limited depth of aeration, low utilization of oxygen, and non-uniform gas distribution. Moreover, the motors of conventional aerators are located above the liquid level, and are prone to failure due to high operating temperatures.